Akademik Veri Yönetim Sistemi
MIKROBIYOLOJI BULTENI, cilt.55, sa.4, ss.492-506, 2021 (SCI-Expanded)
In Turkey, the seven-valent pneumococcal conjugated vaccine (PCV7) was included in the childhood national immunization programme in April 2008 and was replaced by the 13-valent pneumococcal conjugated vaccine (PCV13) in April 2011. In this retrospective, single-center study, it was aimed to determine the serotype distribution and antimicrobial resistance in Streptococcus pneumoniae isolates of pediatric patients with invasive pneumococcal disease (IPD) after the introduction of PVC7 and PVC13. Fifty pediatric patients diagnosed with meningitis and sepsis/bacteremia between October 2009 and October 2019 were included in the study. The pediatric patient group consisted of previously healthy patients diagnosed with meningitis and sepsis/bacteremia with S.pneumoniae isolated in their blood or cerebrospinal fluids. Patients with pneumonia-associated bacteremia and empyema were not included in the study. Serotyping of the isolates was performed by Quellung reaction using specific antisera (Statens Serum Institute, Denmark) and antibiotic (penicillin and ceftriaxone) susceptibility was determined by antibiotic gradient method based on Clinical Laboratory Standards Institute (CLSI) criteria. Of the children, 29 (58%) were boys and 21 (42%) were girls. The median age of the patients was 19 months (1 month-18 year). When the children under the age of five were evaluated, it was found that 30 (79%) patients were diagnosed with occult bacteremia/sepsis and 8 (21%) with meningitis. The overall annual incidence rate of IPD among the healthy children aged <5 years decreased significantly from 9.35/100000 to 0.83/100000 (p<0.001). Serotype identification was determined for 44 of 50 pneumococcal isolates. However, since six patients with underlying disease were not included in the evaluation, the remaining 38 isolates were found to be one of the serotypes included in PCV7 and PCV13 at a rate of 28.9% (n=11) and 44.7% (n=17), respectively. While the rate of PCV13 serotypes seen in the PCV7 period was 81.8%, this rate decreased to 29.6% within eight years after PCV13 administration. The rate of non-vaccine serotypes was determined as 54.5% in PCV7 period and 70.3% in PCV13 period. The rate of non-vaccine serotypes in patients under 5 years was 60% in the period of PCV7 and 75% in the period of PCV13. The proportion of non-vaccine serotypes has increased over time. However, this difference was not statistically significant (p>0.05). The most common serotypes detected in isolates were 19F, 23F, 7F, 31 and 24B. According to the minimum inhibitory concentration values of the isolates recovered from patients with meningitis, penicillin and ceftriaxone resistance rates were found as 43.9% and 9.8%, respectively. In conclusion, our study showed that there was a 91.1% decrease in the incidence of IPD in healthy children aged under five years after the implementation of PCV7 and PCV13. It was determined that while the rate of serotypes in vaccine content decreased, there was an increase in non-vaccine serotypes. In addition no significant change was observed in antibiotic resistance rates over the years.